Carrier Dynamics in Organolead Halide Perovskites

4th European Chemistry CongressMay 11-13, 2017 Barcelona, Spain

Encyclopedia of Bioanalytical Methods for Bioavailability and Bioequivalence Studies of P Two-dimensional (2D) layered perovskites
((A)2(CH3NH3)n−1MnX3n+1, where A is a large aliphatic or aromatic alkylammonium cation working as an insulating layer,
M is the metal cation, and X is the halide anion) have already emerged as an attractive material for applications in photovoltaics and
other optoelectronic devices. Recent reports have demonstrated that the 2D layered perovskite films actually comprised multiple
perovskite phases (with various n values from 1, 2, 3 and 4 to near ), even though the films were intended to be prepared as a
single-phase. This hybrid feature seems to be ineluctable in fabricating 2D films. However, two important questions remain yet-to-beanswered:
first, how the different perovskite phases align in the hybrid films; second, whether the band alignment between different
phases induces energy funneling or instead charge separation. The latter is especially important because it dictates the application
of these hybrid 2D perovskite films: energy funneling is useful for lightemitting applications, whereas charge separation would be
more beneficial for light conversion or detection. Herein, we studied the charge carrier dynamics in 2D multi-layered perovskite films
using ultrafast transient absorption and photoluminescence spectroscopy. Researchers found that multiple perovskite phases inside
2D layered perovskite film (including n = 2, 3, 4 and ≈ ∞) naturally align in the order of n along the direction perpendicular to the
substrate. Driven by the band alignment between 2D perovskites phases, researchers observed consecutive photoinduced electron
transfer from small-n to large-n phases and hole transfer in the opposite direction on hundreds of picoseconds inside the 2D film
of ~358 nm thickness. This internal charge transfer efficiently separates electrons and holes to the upper and bottom surfaces of the
films, which is a unique property beneficial for applications in photovoltaics and other optoelectronics devices.